A continuing demand exists for a simple, inexpensive mechanical device which can be used to change the source of liquid(s) to be delivered through the device. The need for such devices is commonly seen in conjunction with the use of marine engines, where it is desirable to flush corrosive saline water from the engines, particularly when temporarily discontinuing their use. This is because waters upon which boats are operated are contaminated to at least some degree with salts or other harmful minerals, or with particulates such as mud and silt; if such contaminants are allowed to stay in the engine, scaling, corrosion and/or erosion can occur. As a result, there are concomitant adverse effects on engine life and maintenance costs.
In this document, the term "seawater," while used to particularly describe saline marine waters, also shall be understood to include and generally describe any undesirable or contaminated water or other fluid, it being understood that such fluids may not necessarily be seawater but may be fresh or brackish waters that nevertheless may contain contaminants which need to be flushed from an apparatus by another fluid. Further, such reference might be, instead of to water, to one fluid in an industrial setting where flushing with a second fluid would be desirable. Further, the flush valve described herein may have other uses and purposes familiar to those to whom this specification is addressed.
Devices of the character described above which provide the general capabilities desired have heretofore been proposed. Those of which I am aware are disclosed in U.S. Pat. No. 4,619,618 issued Oct. 28, 1986, to Patti for FRESH WATER FLUSHING KIT; and U.S. Pat. No. 3,550,612 issued Dec. 29, 1970, to Maxon for PURGE VALVE FOR COOLING FLUID CONDUIT SYSTEMS.
For the most part, the patent documents identified in the preceding paragraph disclose devices which include an elongated pipe portion to which multiple flow regulating devices are appended. Such devices inherently require proper performance of sequential steps to begin a flushing operation, and then a reversal of those steps to terminate the flushing and thus allow normal coolant flow. In fact, the combination of complicated operational procedures, fluid flow design, and the normal physical location of such prior art devices often presents the risk that an improper operational procedure will expose a vessel to taking on seawater, thus giving rise to the potential danger of sinking.
In Patti, a complicated assembly of components is seen. Patti's device consists of a long tubular assembly having a shutoff valve between a seawater inlet and outlet, a second shutoff valve between a fresh water inlet and outlet, as well as a closure device (cover plate) at the fresh water inlet. As the cover plate must be removed and replaced for each flush operation, the opportunity for improper operation and resultant danger to the vessel is ever present.
In Maxon, a device including a ball valve is situated in the saline coolant flow line. The ball in the valve is displaced upon normal flow of saline coolant, thus allowing passage of the coolant. When the flushing liquid is fed to the device, the ball valve is displaced in the opposite direction, described as downwardly to a valve seat, to thereby prevent saline coolant from being introduced to the engine through the valve. While the Maxon device avoids the operational complexity of Patti, the constant exposure of the various valve seats to corrosive saline coolant creates the likelihood of deposition of contaminants on and corrosion of the seat, thus creating an inherently unreliable liquid seal over the lifetime of a vessel. Over time, such a result would likely compromise the purity of any flushing fluid.
Another common deficiency of the heretofore available flush valves is the absence of a readily apparent visual indication to the operator that the flow of liquid into the engine may occur and that such flow is from the desired source. The advantage of such an indication is important and self-evident.